MANILA - Magma continues to deform the Taal Volcano island, its movement resulting in an “uplift” of the volcano, and could be an indication of a possible explosive eruption, the Philippine Institute of Volcanology and Seismology (Phivolcs) said Monday.
“Definitely may papaakyat na magma. May nagsusupply pa doon (Definitely there is rising magma. There’s magma being supplied),” Phivolcs Director Renato Solidum said in a press conference on Monday morning.
Phivolcs said despite observations of a calm Taal volcano in the recent days, with only a steady steam emission and “infrequent weak explosions” that generated ash plumes as high at 500 to 100 meters, volcanic activities underground showed otherwise.
Phivolcs noted that frequent volcanic earthquakes and the increasing levels of sulfur dioxide were indications of magma movement, which may lead to a possible eruption.
As of posting, there have been 714 volcanic earthquakes in the vicinity of Taal Volcano since January 12, 1 p.m., based on the Philippine Seismic Network (PSN). Of that number, 176 were at magnitude 1.2 to 4.1 and were felt at Intensities I to V. Based on the Taal Volcano Network, which can record small earthquakes undetectable by the PSN, there were 673 volcanic earthquakes including 12 low-frequency earthquake.
Solidum said the volcanic earthquakes could mean that the water in the island and the surrounding lake was boiling and could result in steam-driven eruptions.
He said the magma movement has also resulted in an “uplift” of the volcano, causing fissures or cracks on the ground, like those earlier detected in several towns in Batangas.
“Taal Lake is being stretched, the land is being uplifted, water level is going down besides the water from the main crater being vaporized,” Solidum explained. Last week, Phivolcs monitoring showed that the crater lake was vaporized by the continued volcanic activity in Taal. It also revealed smaller craters within the main crater.
Phivolcs Volcano Monitoring and Eruption Prediction Division chief Mariton Bornas said that most of the volcano island has swelled and only the northeastern flank subsiding.
Solidum said the high level of sulfur dioxide emission measured (at 4,353 tonnes a day on Sunday and Monday) was also a sign of magma.
Bornas earlier explained that sulfur dioxide separates from magma only when it is near the surface.
“The increasing (volcanic) gas is an indication that there is magma that can be a cause of possible explosion,” Solidum said.
He also raised concerns that Taal Volcano is now an “open system” with no obstructions in the crater in case it has a major eruption.
Phivolcs did not comment on evacuation, except that the volcano island should not be visited. It said it was up to the local government units to assess if people living in high-risk areas within the 14-kilometer radius of Taal Volcano’s crater should be momentarily allowed to return to their houses.
Solidum maintained, however, that the high-risk areas should be closely observed, especially since they are at risk of experiencing base surges, a deadly lateral blast of hot gas, ash, and volcanic debris.
He said in case of eruption, a smaller plume at 3 to 5 kilometers in height can cause ash fall in Cavite but a major eruption creating ash columns higher than 5 kilometers will bring ash to Metro Manila, Laguna, and some parts of Rizal and northern Quezon.
Alert level 4 remains up in Taal Volcano, which means hazardous explosive eruption can be expected within hours or days.